Electric transformers and like



Fb. 7, 1956 5 5NN|$ ELECTRIC TRANSFORMERS AND LIKE APPARATUS Filed Nov.9, 1951 Inventor- Arthur S. Ennis, by WW His Attorney.

United States Patent 1 2,734,096 ELECTRIC TRANSFORMERS AN 1) LKKEAPPARATUS Arthur Samuel Ennis, Sale, England, assignor to General.Electric Company, a corporation of New York Application November 9,1351, Serial No. 255,605 1 Claim. (Cl. 174-15} This invention relates toelectric transformers and the like and is concerned with the reductionof noise emanating therefrom.

Where an electric transformer is mounted within a liquid filled tank,vibration originating in the core of the transformer and radiated fromthe tank as noise is trans mitted from the core to the tank walls by twomain paths, the first through the solid connections, such as themounting supports between the transformer and the tank and the secondthrough the liquid, generally oil, occupying the space between thetransformer and the tank walls. It therefore follows that an arrangementfor reducing noise radiated from the transformer tank should aim atattenuating the vibration transmitted by both the paths.

In transformer or like apparatus according to the pres ent invention, aninner tank, in which is mounted the transformer proper for immersion ina liquid, usually oil, is resiliently mounted within an outer tank whichencloses an air space surrounding the inner tank, and means are providedfor maintaining a flow of cooling liquid over the outer surfaces of theinner tank. The air space between the two tanks will act as a soundbarrier between the transformer and the walls of the outer tank whilstthe resilient mounting will reduce the vibration which is transmittedthrough the solid connections between the transformer and the outertank, with the result that noise radiated from the apparatus will besubstantially reduced. It has also been found that the cooling of thetransformer may be enhanced in apparatus constructed in accordance withthe invention.

It will be appreciated that the mounting of the inner tank must beresilient with respect to the outer tank at all places where there is asolid connection between the transformer and the outer tank; thisincludes for example, the electric leads passing from the transformer tothe exterior of the outer tank, which leads will usually includeinsulated conductors sealed through the walls of the tanks.

Advantageously in carrying out the invention cooling liquid is sprayedon to the top surface of the inner tank and allowed to flow down theside surfaces, an external pump being provided which withdraws theliquid from the bottom of the outer tank and recirculates it to thespray through a cooler.

In order that the invention may be more clearly understood referencewill now be made to the accompanying drawing in which the single figureshows a preferred embodiment of the invention.

In the embodiment shown, a transformer 1 is in1- mersed in oil in aninner tank 2 which is mounted on spring supports 3 in an outer tank 4enclosing an air space 5 surrounding the inner tank 2. The electricalconnections from the transformer pass to the exterior of the outer tank4 by way of conductors 6 sealed in insulating bushings 7 through thewalls of the tanks, these conductors being joined together by a flexibleconnection 8 to ensure that the inner tank 2 is mounted resiliently inall respects.

A perforated pipe 9 is arranged within the outer tank 4, and above theinner tank 2 on to the top surface 10 of which it continuously sprays acooling liquid as indicated by the dotted lines. This liquid comes froma reservoir 11 mounted above the outer tank 4 and having a capacity atleast equal to the volume of the 2,734,096 Patented Feb. '7, 1956 spacebetween the two tanks plus that of a cooler 12 through which an externalpump 13 passes the liquid back to the reservoir 11, the cooler 12comprising a nest of vertical tubes mounted to the side of the outertank. The pump 13 is such as will maintain a dry sump to the outer tank4, while allowing a copious flow of cooling fluid over the top and sidesof the inner tank 2 from the reservoir 11 above. In this way, when thepump 13 is operating there will always be an air space 5 between the twotanks which will act as a sound barrier.

The reservoir 11 forms part of a safety arrangement which comes intooperation should the pump 13 fail. Normally the cooling liquid for thespray is pumped through the cooler 12 to the reservoir 11, but valves14, 15, preferably automatic, are arranged so that on stoppage of thepump 13 the cooler 12 is or may be connected directly between top andbottom of the outer tank 4. At the same time, liquid from the reservoir11 floods the space 5 between the inner and outer tanks so that the unitthen operates under a normal thermosyphon cooling system. In such anemergency condition of course, since there is no longer an air barrierbetween the tanks the only noise reduction will be that effected by theresilient mounting. The rating of the transformer may also be reduced insuch a condition due to less efficient cooling.

If necessary the cooling of the inner tank 2 may be enhanced byproviding cooling tubes or fins (not shown) on its exterior and in somecases it may even be necessary to employ forced circulation of the oilin the inner tank to increase the cooling still further.

What I claim is:

An electric transformer or like apparatus comprising an inner tank, atransformer proper immersed in a liquid and mounted within said innertank, an outer tank enclosing an air space which substantiallycompletely sur rounds said inner tank, means for resiliently mountingsaid inner tank within said outer tank, a cooling liquid within saidouter tank, means for maintaining a flow of said cooling liquid over theouter surfaces of said inner tank, said flow maintaining meanscomprising a reservoir mounted above said outer tank, spray means withinsaid outer tank and connected to said reservoir, a cooler, and pumpmeans connected to circulate said cooling liquid from the bottom of saidouter tank upwardly through said cooler to said reservoir, and thenceonto the top of said inner tank by way of said spray means, said pumpmeans having sufiicient capacity to maintain the level of said liquid insaid outer tank below the bottom of said inner tank while allowing acopious flow of said cooling liquid over the top and sides of said innertank from said reservoir, said reservoir having a capacity at leastequal to the volume of the space between said tanks plus the volume ofsaid cooler, and valve means arranged such that said cooler may bealternatively connected directly between the top and bottom of saidouter tank to cool said transformer by a thermosyphon action or betweensaid reservoir and said pump means, said transformer containing asufficient quantity of said cooling liquid to flood the space betweensaid inner and outer tanks upon stoppage of said pump means.

References Cited in the file of this patent UNITED STATES PATENTS1,700,839 Gay Feb. 5, 1929 2,083,611 Marshall June 15, 1937 2,138,607Larsen Nov. 29, 1938 2,314,464 Shaw Mar. 23, 1943 2,425,404 Touborg Aug.12, 1947 2,440,556 Paluev Apr. 27, 1948 2,505,854 Curzon May 2, 19502,561,738 Hill July 24, 1951

